I'm aware of the general meaning of the initialization, but what is the equivalent MATLAB input of the above for an .m file?

(2) (also from the R file) I'm trying to generate from an N x 2 matrix a vector whose number of entries is the number of groups of the data, and whose entries give the number of members in the group. For example,

2 13 15 17 29 21 2

The above has 2 groups (groups represented by the second column), group 1 and group 2. Each group has 3 members, so the vector would look like

[3 3]

The R code for the above is

for (i in 1:N) # n = vector giving number in each group n[group[i]] = n[group[i]] + 1